The long term success of treating arrhythmias often depends on the determination of the exact tissue or trigger in the heart causing the arrhythmia so that the malfunctioning tissue can be ablated and the normal rhythm of the heart restored. Ablation of arrhythmias, like atrial fibrillation, whether paroxysmal or chronic, typically involves the simultaneous mapping of a region of cardiac tissue with a multi-electrode catheter in order to identify and ablate tissue sources or drivers of arrhythmias. Maps of cardiac activation often include an electrogram signal recording displaying a progression of electrode depolarizations in the target tissue region in order to identify cardiac activation times to determine arrhythmic sites. The activation times of the electrode depolarizations are often determined by visual analysis of the electrogram, which includes looking for the tallest peak or steepest valley of deflections or the time of zero-crossing for a bipolar or near-field electrogram, or looking for the timing of the most negative slope for a unipolar or far field electrogram.
However, in complex electrograms, as in those in patients with atrial fibrillation, each depolarization may include several non-discrete deflections making an accurate determination of cardiac activation times cumbersome and ambiguous. Thus, current methods and systems of determining activation times are inaccurate thereby reducing the accuracy of atrial fibrillation treatments.